mod_pubsub

publish and subscribe messaging for the web.

What is mod_pubsub?

mod_pubsub is a set of libraries, tools, and scripts that enable publish and subscribe messaging over HTTP. mod_pubsub extends Apacheby running within its mod_perl Web Server module.

What's the benefit of developing with mod_pubsub?

Real-time data delivery to and from Web Browsers without refreshing; without installing client-side software; and without Applets, ActiveX, or Plug-ins. This is useful for live portals and dashboards, and Web Browser notifications.

Exactly how do mod_pubsub's connections stay open?

mod_pubsub's clients do not poll the server every so often. Instead, like Jabber, a PubSub Server holds open the connection socket to its clients. The main difference between mod_pubsub and Jabber is that we use standard HTTP as our wire format, whereas Jabber uses its own XML-based protocol. (Yes, we know that people think HTTP is a polling protocol... but it's not necessarily.)

How about other Web Servers, or if I have no Web Server?

mod_pubsub's scripts can be used with other Web Servers, as well. We also provide a separate, feature-compatible standalone PubSub Server written in Python that is run from the command-line.

Are there any other products like mod_pubsub?

Similar projects include Pushlets, Jabber, and XMLHTTP. Unlike mod_pubsub, Pushlets can only maintain a few simultaneous connections, and require Java programming. With mod_pubsub, if you know how to use HTTP, you can do PubSub. Unlike Jabber, which uses its own XML-based protocol, we use standard HTTP. And unlike XMLHTTP, we are not Microsoft-only.

What languages does mod_pubsub support?

Besides a zero-install JavaScript library that runs within a Browser's Web page, we also offer embeddable libraries to connect applications written in C; Visual Basic, Visual C++, and C# using ActiveX, COM, .NET, or PocketPC; Python, Perl, PHP, and Ruby; and Java. Our goal is to connect as much as possible.

What license is mod_pubsub distributed under?

BSD-style, baby!

Cool, how can I try mod_pubsub?

Download the tarball from our SourceForge project page. Also, join our mailing lists to keep up to date on the development of mod_pubsub. And feel free to peruse some of our technical documents: Developer Guide, PubSub Protocol, and JavaScript Library Reference.

What is mod_pubsub's relationship to KnowNow, Inc.?

KnowNow released a great deal of code under an Open Source license, and the mod-pubsub group formed to extend that codebase. The two codebases are developing entirely separately and are optimized for different uses, although we make some effort to keep the Pubsub Protocol and APIs aligned. There is no contractual or financial relationship between the two organizations.